This invention relates to rotary mower blades mounted on power mowers used, e.g., for cutting lawns, and more particularly to a rotary mower blade having a combination of auxiliary features that alternatively enhance bag filling, side delivery and mulching.
A rotary mower blade is designed to have varying features. The blade itself resembles a flat bar that is rotated about a center axis with opposing blade portions extended from the axis and each blade portion having a leading beveled edge for cutting. It is mounted on a powered mower (riding or walk behind mower). The blade is rapidly rotated about the axis with each blade portion participating in the operation of cutting, e.g., grass of a residential lawn but including any type of grass cutting (golf courses, grounds surrounding industrial and commercial complexes, etc.). Such cutting is the primary feature of the blade.
The mower operator may wish to simply leave the cut grass lay on the lawn for fertilization and to avoid the task of bagging and disposing of the grass. In this event, the operator will prefer that the grass be mulched, i.e., cut into smaller pieces. Mulching is accomplished by providing a set of teeth on the trailing edge of the blade portion. The teeth are projected above the plane of the blade body and the grass that is cut by the leading edge is re-cut by the trailing edge teeth to produce the mulching action.
Alternatively, the mower operator may prefer to cut and bag the mowed grass. Bagging is achieved by taking advantage of the propulsion that is applied to the cut grass when impacted by the blade. The propelled grass is guided through or along a guide way and into a bag that is provided on the mower for that purpose. Still further, the guide way may be provided to simply deliver the grass through a side opening and onto the ground or lawn. The propulsion and guiding of the grass can be enhanced by providing the rear edge of the blade portions with an uplifting ramp that creates an upward air flow that directs the cut grass accordingly.
The problem to which the present invention is addressed is that mulching blades are not a preferred blade type for bagging (or side delivery) and the bagging blades are not suitable for mulching. Yet operators will alternate between bagging and mulching and using current blade designs, a selection has to be made as to blade type and one or the other of the operations is less efficient unless the blade is changed.
The present invention is a modification of the mower blade which includes a combination of mulching teeth and ramp portion at the trailing edge. Preferably the trailing edge is provided with a ramp portion at the outer end and cutting teeth inwardly of the ramp portion. The blade continues to produce a mulching action but not at the blade tips. Nevertheless, in a mulching operation the grass is flung around within the blade housing or deck in a swirling-like motion and most or all of the grass is repeatedly cut and re-cut by the mulching teeth before being ejected onto the ground.
The ramped blade tip (although contributing to the swirling action) is primarily intended to enhance the bagging operation. The rapidly rotating ramp portion produces a lifting action to the underlying grass (cut or uncut) and thereby aids the cutting action, and also an upward positive air flow that directs the severed grass toward an opened guide way or tube for side discharge or bagging. The present invention accordingly provides a blade that accomplishes both mulching enhancement and bag filling or side delivery enhancement.